According to the gas-insulated apparatus of a gas-insulated opening/closing apparatus, a gas-insulated transformation apparatus, a gas-insulated bus or the like, a plurality of vessels are connected in airtight, and a power apparatus main body of a circuit breaker, a disconnecting switch, a grounding switch, a power conductor or the like is included in the hermetically closed vessel connected in airtight and enclosed with an insulating gas.
According to the gas-insulated power apparatus, for example, a vessel of a gas-insulated bus led from the gas-insulated opening/closing apparatus or the like is coupled to a vessel of the gas-insulted opening/closing apparatus by fastening flange portions of respectives thereof by a bolt. Further, there is a case in which the led out gas-insulated bus is prolonged, and in this case, a bellows in series coupling is used for the vessel per se of the gas-insulated bus in order to absorb thermal elongation/contraction of the gas-insulated bus per se (for example, refer to Patent Reference 1).    Patent Reference 1: JP-A-2002-51440 (FIG. 1 and explanation thereof)